Such a snow groomer is known from EP 0 895 495 B1. The snow groomer is a hybrid vehicle in which a diesel engine drives an electric generator which feeds an electric traction drive, specifically the chain drive, via power electronics. The chain drive respectively has a sprocket wheel for each of the two traction chains, which sprocket wheel drives the respective traction chain. Each sprocket wheel is driven by one electric motor in each case. The snow groomer also has a rear-mounted cutter whose cutter drive is also formed by an electric motor which is fed by means of the power electronics via the generator.
WO 94/09548 A1 discloses a similar diesel-electric snow groomer in which likewise a diesel engine drives a generator which feeds electric traction drives and cutter drives via corresponding power electronics.
The object of the invention is to provide a snow groomer of the type mentioned at the beginning which makes possible a sufficient emergency operating mode.
This object is achieved in that two generators which are connected in parallel are provided between the internal combustion engine and the power electronics. The two electric generators preferably have the same power. Each generator preferably has a power between 100 and 200 kW, preferably 140 kW. Since the two generators which are connected in parallel act as a double generator in the normal operating mode of the snow groomer, twice the power, in particular between 200 and 400 kW, preferably 280 kW, is therefore available. By virtue of the solution according to the invention, if a generator fails or in the event of a fault in a generator the second generator is still available to change a corresponding function of the snow groomer, such as in particular a driving function, a cutting function, a winching function or the like, into a safe state and/or to ensure an emergency operating mode. A traction drive, in particular a sprocket wheel drive, a cutting shaft drive for a rear-mounted cutter or a winch drive for a winch which is arranged on the snow groomer is provided as a rotational functional drive. Other rotational secondary drives of the snow groomer are also covered by the term functional drive.
The solution according to the invention provides a redundant system.
In one refinement of the invention, the internal combustion engine is assigned a transfer transmission to which the two generators are connected on the output side. The two generators are connected mechanically by flanges to the transfer transmission. This has the advantage that energy is assisted or fed back, in particular during downhill travel or during braking processes of the snow groomer, via the transfer transmission and the internal combustion engine. The corresponding, fed-back energy can be taken up by the internal combustion engine by increasing the rotational speed.
In a further refinement, traction motors for a chain drive, at least one cutting shaft drive and/or a winch drive, are provided as functional drives. As a result, the central components of a snow groomer which is used to treat a snow piste surface are electrified.
In a further refinement of the invention, the electric motors of the functional drives are formed by synchronous motors. This refinement is advantageous for snow groomers since a high level of torque is already available at low rotational speeds.
In a further refinement of the invention, the power electronics are constructed as a direct current intermediate circuit. This is advantageous for actuation with direct-current-operated synchronous motors.
In a further refinement of the invention, current rectifiers are assigned to the generators. Preferably, a frequency converter is integrated in a housing of each electric generator.
In a further refinement of the invention, an electric switching element, which can electrically disconnect the generator from the power electronics, is provided for each generator. In particular a relay, which is installed in an electrical line between the power electronics and the assigned generator, is provided as an electric switching element. The solution makes it possible to disconnect the generator from the drive system in the event of a fault or else if the generator fails, and to provide an emergency operating mode via the other, still functioning generator.
In a further refinement of the invention, an electronic controller is provided which activates the switching element as a function of functional monitoring of the generator for disconnection of the generator from the power electronics. The electronic controller has means for monitoring the functioning of each generator. Corresponding data are transmitted to a comparison and evaluation unit of the electronic controller, which then performs, as a function of the result of the comparison and of the evaluation, corresponding actuation of the electric switching element for disconnecting the generator.
Further advantages and features of the invention emerge from the claims and from the following description of a preferred exemplary embodiment of the invention which is illustrated on the basis of the drawings.